Pointer Usage: Operations may be performed with pointer
button 1, or in some cases, with the keyboard. Many common calculator
operations have keyboard accelerators. To quit, press pointer button 3 on
the AC key of the TI calculator, or the ON key of the HP calculator.

Calculator
Key Usage (TI mode): The numbered keys, the +/- key, and the +, -, *, /,
and = keys all do exactly what you would expect them to. It should be
noted that the operators obey the standard rules of precedence. Thus, entering
"3+4*5=" results in "23", not "35". The parentheses can be used to override
this. For example, "(1+2+3)*(4+5+6)=" results in "6*15=90".

The entire
number in the calculator display can be selected, in order to paste the
result of a calculation into text.

The action procedures associated with
each function are given below. These are useful if you are interested in
defining a custom calculator. The action used for all digit keys is digit(n)
,
where n is the corresponding digit, 0..9.

1/x

Replaces the number in the display
with its reciprocal. The corresponding action procedure is reciprocal().

x^2

Squares the number in the display. The corresponding action procedure
is square().

SQRT

Takes the square root of the number in the display. The
corresponding action procedure is squareRoot().

CE/C

When pressed once,
clears the number in the display without clearing the state of the machine.
Allows you to re-enter a number if you make a mistake. Pressing it twice
clears the state, also. The corresponding action procedure for TI mode is
clear().

AC

Clears the display, the state, and the memory. Pressing it with
the third pointer button turns off the calculator, in that it exits the
program. The action procedure to clear the state is off(); to quit, quit().

INV

Invert function. See the individual function keys for details. The corresponding
action procedure is inverse().

sin

Computes the sine of the number in the
display, as interpreted by the current DRG mode (see DRG, below). If inverted,
it computes the arcsine. The corresponding action procedure is sine().

cos

Computes the cosine, or arccosine when inverted. The corresponding action
procedure is cosine().

tan

Computes the tangent, or arctangent when inverted.
The corresponding action procedure is tangent().

DRG

Changes the DRG mode,
as indicated by 'DEG', 'RAD', or 'GRAD' at the bottom of of the calculator ``liquid
crystal'' display. When in 'DEG' mode, numbers in the display are taken as being
degrees. In 'RAD' mode, numbers are in radians, and in 'GRAD' mode, numbers
are in grads. When inverted, the DRG key has a feature of converting degrees
to radians to grads and vice-versa. Example: put the calculator into 'DEG'
mode, and enter "45 INV DRG". The display should now show something along
the lines of ".785398", which is 45 degrees converted to radians. The corresponding
action procedure is degree().

e

The constant 'e'. (2.7182818...). The corresponding
action procedure is e().

Calculates the log (base 10) of the number in the display.
When inverted, it raises "10.0" to the number in the display. For example,
entering "3 INV log" should result in "1000". The corresponding action procedure
is logarithm().

ln

Calculates the log (base e) of the number in the display.
When inverted, it raises "e" to the number in the display. For example,
entering "e ln" should result in "1". The corresponding action procedure
is naturalLog().

y^x

Raises the number on the left to the power of the number
on the right. For example "2 y^x 3 =" results in "8", which is 2^3. For
a further example, "(1+2+3) y^x (1+2) =" equals "6 y^x 3" which equals "216".
The corresponding action procedure is power().

PI

The constant 'pi'. (3.1415927....)
The corresponding action procedure is pi().

x!

Computes the factorial of
the number in the display. The number in the display must be an integer
in the range 0-500, though, depending on your math library, it might overflow
long before that. The corresponding action procedure is factorial().

(

Left
parenthesis. The corresponding action procedure for TI calculators is leftParen().

)

Right parenthesis. The corresponding action procedure for TI calculators
is rightParen().

/

Division. The corresponding action procedure is divide().

*

Multiplication. The corresponding action procedure is multiply().

-

Subtraction.
The corresponding action procedure is subtract().

+

Addition. The corresponding
action procedure is add().

=

Perform calculation. The TI-specific action
procedure is equal().

STO

Copies the number in the display to the memory
location. The corresponding action procedure is store().

RCL

Copies the number
from the memory location to the display. The corresponding action procedure
is recall().

SUM

Adds the number in the display to the number in the memory
location. The corresponding action procedure is sum().

EXC

Swaps the number
in the display with the number in the memory location. The corresponding
action procedure for the TI calculator is exchange().

+/-

Negate; change
sign. The corresponding action procedure is negate().

.

Decimal point. The
action procedure is decimal().

Calculator Key Usage (RPN mode): The number
keys, CHS (change sign), +, -, *, /, and ENTR keys all do exactly what
you would expect them to do. Many of the remaining keys are the same as
in TI mode. The differences are detailed below. The action procedure for
the ENTR key is enter().

<-

This is a backspace key that can be used if you
make a mistake while entering a number. It will erase digits from the display.
(See BUGS). Inverse backspace will clear the X register. The corresponding
action procedure is back().

ON

Clears the display, the state, and the memory.
Pressing it with the third pointer button turns off the calculator, in
that it exits the program. To clear state, the action procedure is off;
to quit, quit().

INV

Inverts the meaning of the function keys. This would
be the f key on an HP calculator, but xcalc does not display multiple
legends on each key. See the individual function keys for details.

10^x

Raises
"10.0" to the number in the top of the stack. When inverted, it calculates
the log (base 10) of the number in the display. The corresponding action
procedure is tenpower().

e^x

Raises "e" to the number in the top of the stack.
When inverted, it calculates the log (base e) of the number in the display.
The action procedure is epower().

STO

Copies the number in the top of the
stack to a memory location. There are 10 memory locations. The desired
memory is specified by following this key with a digit key.

RCL

Pushes the
number from the specified memory location onto the stack.

SUM

Adds the number
on top of the stack to the number in the specified memory location.

x:y

Exchanges the numbers in the top two stack positions, the X and Y registers.
The corresponding action procedure is XexchangeY().

R v

Rolls the stack
downward. When inverted, it rolls the stack upward. The corresponding action
procedure is roll().

blank

These keys were used for programming functions
on the HP-10C. Their functionality has not been duplicated in xcalc.

Finally,
there are two additional action procedures: bell(), which rings the bell;
and selection(), which performs a cut on the entire number in the calculator's
``liquid crystal'' display.

Accelerators are shortcuts for entering
commands. xcalc provides some sample keyboard accelerators; also users
can customize accelerators. The numeric keypad accelerators provided by
xcalc should be intuitively correct. The accelerators defined by xcalc on
the main keyboard are given below:

xcalc has an enormous
application defaults file which specifies the position, label, and function
of each key on the calculator. It also gives translations to serve as keyboard
accelerators. Because these resources are not specified in the source code,
you can create a customized calculator by writing a private application
defaults file, using the Athena Command and Form widget resources to specify
the size and position of buttons, the label for each button, and the function
of each button.

The foreground and background colors of each calculator
key can be individually specified. For the TI calculator, a classical color
resource specification might be:

In order to specify resources,
it is useful to know the hierarchy of the widgets which compose xcalc.
In the notation below, indentation indicates hierarchical structure. The
widget class name is given first, followed by the widget instance name.